Apparatus for transforming sound into electrical energy



' March 4, 1930.

H. c. HAYES 1,749,284

APPARATUS FOR TRANSFORMING SOUND INTO ELECTRICAL ENERGY Original Filed June 30, 1924 INVEN TOR. Haw g 6f Hayes ATTORNEYS.

Patented Mar, 1930 PATENT ounce HARVEY C. HAYES, OF WASHINGTON, DISTRICT OF COLUMBIA APPARATUS FOR TBANSFORMING- SbUND INTO ELECTRICAL ENERGY Original application filed June 30, 1924, Serial No. 723,427. Patent No. 1,729,383, dated September 24,

1929. Divided and this application filed November 11, 1927. SerialNo. 232,701.

(GRANTED mar. mm or union 3, 1883, AS AMENDED APRIL a0, 1928; 370 o. a. 7575 stantially no impinging of the sonic undulations upon a diaphragm, but one in which the diaphragm will move with the movement of the fluid about it.

This object employs the utilization of the viscosity of the fluid in which the diaphragm is mounted and this serves a useful purpose in the production of a micro hone which will more faithfully transform t e energy of the sonic undulations into electrical energy than those types of microphones in which the sound waves vibrate the diaphragm by impinging directly thereon.

y invention consists substantially in the construction, combination and arrangement of parts associated therewith or as will be more fully hereinafter set forth as shown by the accompanying drawings and finally pointed out in the appended claims.

Reference is to be had to theaccompanying drawings forming a part of this specification in which like reference characters indicate corresponding parts throughout the several views and in which:

Figure 1 is a sectional view through my improved microphone, I

- Figure 2 is a perspective view of the same but with the protective dust cap removed,

and

Figure 3 is a perspective view correspond 5 ing to Figure 2, but showing the use of a ribbon-like filament, a portion only of one turn of the filament coil being illustrated.

Referring to the drawings the letters N and S refer to the north and south poles of one magnet, the poles of which are brought into close proximity to each other or the north and south poles of two magnets placed end to end. As the substitution of one magnet for two or vice versa makes very little difference in the operation of the device I will describe it as consisting of two magnets placed end to end in' the'manner shown.

One of the magnets 5 is hollow as shown at 6 or if one magnet is used the hollow portion of the pole upon' the other side of the magnetic gap is filled with material 7 so that the S pole presents a reflecting surface to the sonic vibrations passing through the hollow portion 6. Upon one end of the magnet 5 I have rovided a mouthpiece 3 for the direction 0 speech or other sounds within the hollow portion 6 of the magnet 5 which in turn conducts the vibrations tothe magnetic gap. I

Surrounding the magnetic gap I have rovided a dust cap 8 which serves a multiplicity of functions, one of which is the production of a chamber 4 surrounding the magnetic gap, and others of which are to prevent the accumulation of dust within the magnetic gap, to serve as a means for mounting a diaphragm within the magnetic gap and to prevent the movements of the air surrounding the microphone from reaching the diaphragm.

Within the magnetic gap I have mounted an element 9 which I have chosen to call a diaphragm for Want of a better term. This diaphragm consists of a coil of filamentary or ribbon-like wire of a fineness similar to that of the fine threads of glass that are to be found floating in the air of a glass blowing es tablishment. The mass of such a filament is so small in comparison to its area that the viscosity of the air is suflicient to carry 90 it with it in its movement without any appreciable relative change between the filament and the surrounding air. This coil is secured at its ends to short pieces 1, 2 of relatively stifi' supporting wire, these sup porting wires being in turn secured to the inner ends of a pair of terminals 1, 2.

I-have found that not only will a filament of this type follow the air in- .its larger movements but also it will be carried with it in its smaller movements suchas the compressions and rarefactions in the atmosphere which are generally termed sonic vibrations. The element 9 is constructed as a coil of this fine filamentary conductor which, in the case of the ribbon-like filament, is crinkled as is shown more-clearly in Fig. 3 and is mounted within the magnetic gap in such a manner that when the sonic vibrations pass through the hollow portion 6 of the magnet 5 and impinge upon the face of the pole of the magnet 7 with the result that they are directed into the chamber 4, they pass the turns of the coil 9. As these compressions .and rarefactions pass the individual turns of the coil 9 the viscosity of the fluid surrounding the filamentary conductor act thereon as the fluid attempts to pass the coil 9 and expands and contracts the coil with the result that the flux between the poles N and S is cut by the coil- 9. This movement of the coil 9 within the flux of the magnet induces an electromotive force inthe coil which electromotive force is conducted to an amplifying device connected to the terminals 1 and 2. 1

From the above description it will be seen that I haveproduced a microphone which is substantially non-resonant and which faith-' fully follows the characteristics of the sonic vibrations which are to betransformed'into electrical energy.

It will be understood that the above description and accompanying drawings comprehend only the general and preferred embodiment of my invention and that minor changes in the construction and arrangement of parts may be made within the scope of the appended claims without sacrificing any of the advantages of my'invention.

The invention herein described maybe manufactured and used by or for the Government of the United States for govern-' mental purposes without the payment to me of any royalty thereon or therefor.

What I claim is as follows:

1. An apparatus for'transforming sound into electrical energy, comprising a sound concentrating means, a magnet having circular pole pieces, one of said pole pieces be ing hollow, a magnetic gap between said pole pieces, means for protectin said magnetic gap from extraneous inter erences and a coiled filamentary conductor suspended freely between the two pole pieces.

tween said poles, means for directing sonic vibrations through said conduit and into said magnetic gap and a coiled filamentary conductor freely suspended from its ends within said magnetic gap.

4. In an apparatus of the'character described, the combination of a magnet having a plurality of poles, one of said poles having a conduit therethrough, a magnetic gap between said poles, a protective capsurrounding the pole pieces and forming a chamber surrounding said magnetic gap, means for directing sonic vibrations through said conduit, against the surface of the other pole of said magnetic gap .and into said chamber, and a freely suspended coiled filamentaryconductor disposed within the magnetic. gap.

5. In an apparatus of the character described, the combination of a magnet having a plurality of poles, amagnetic gap between the poles, means for directing sonic vibrations within the magnetic gap and a coiled filamentary conductor formed of a crinkled ribbon and freely suspended within the mag- I netic gap.

6. In an apparatus of the character described, the combination of a magnet having a plurality of poles, one of the poles having a conduit therethrough, a magnetic gap between said poles, means for directing sonic vibrations through said conduit and into said magnetic gap and a coiled filamentary conductor formed of crinkled material and freely suspended from its ends within said magnetic gap.

7. In an apparatus of the character described, the combination of a magnet having a plurality of poles, one of said poles having a conduit therethrough, a magnetic gap between said poles, a protective cap surrounding the pole pieces and formirig a chamber surrounding said magnetic gap, means for directing sonic vibrations through said conduit, against the surface of the other pole of saill magnetic gap and into said chamber, and a coiled filamentary conductor formed of crinkled material and freely suspended within the magnetic gap.

8. In an apparatus of the character de- 1 scribed, the combination of a magnet having a pluralityof poles, one ofsaid poles having a conduit therethrough, a magnetic gap between said poles, a protective cap surrounding the pole pieces and forming a chamber surrounding said magnetic gap, means for directing sonic vibrations through said conduit, against the surface of the other pole of said magnetic gap and into said chamber, a coiled filamentary conductor freely suspended within the magnetic gap, and electric terminals for said coil mounted upon said protective cap.

9. In a device of the class described, a plurality of magnetic poles, said poles being spaced to provide an air-gap between them, a coiled filamentary conductor freely suspended Within said a1r-gap, and means for directing sound impulses toward said conductor.

HARVEY O. HAYES. 

